The invention relates generally to hydraulic systems utilizing charge pumps and more particularly to an improved hydraulic system having a jet pump to augment the charge pump.
In the past, in hydraulic systems having a main pump and a charge pump, the charge pump was always sized so as to be large enough to supply the demands of the main pump under all conditions. Even with proper sizing of the charge and main pumps for all normal conditions, it has been found that at new elevated operating temperatures and low charge pump speeds that a properly sized charge pump is inadequate to keep up with the leakage through the system and a costly, larger charge pump is required to provide adequate fluid to the main pump to prevent destructive cavitation therein.